Further studies of the rate of exchange of albumin between the plasma and interstitial spaces of the lung will be undertaken to further define the two compartment model. The concentration and exchange rates of other proteins in the interstitial space will be determined and appropriate analytic techniques refined. The anatomic sites of protein transfer and location within the interstitial space of the lung will be sought. When the normal values have been determined, the changes induced by endotoxin will be analyzed, both with respect to pulmonary functional changes and to alterations in protein distribution in the lung. Pulmonary capillary permeability and its influence on lung water accumulation will be further studied with a multiple indicator dilution technique. Methods to obtain estimates of capillary surface area will be examined. Studies in patients with respiratory distress will continue to identify the significance of capillary permeability changes in various disease states and the influence of therapeutic maneuvers analyzed.